Washington -LRB- CNN -RRB- -- It was a tale of two rulings -- the best of times and the worst of times for Obamacare in the federal appeals courts .

First , a three-judge panel of the D.C. Circuit court of appeals ruled Tuesday against a key component of the law -- the federal subsidies for millions of people who signed up for health coverage .

The 2-1 decision created a legal path for a possible Supreme Court case that could essentially gut the 2010 Affordable Care Act , which passed with zero GOP votes .

A few hours later , all three judges on a 4th Circuit panel in Virginia decided the opposite by declaring the subsidies legal and proper .

What the court decisions mean for you

Opposing rulings

The opposing rulings increased the chances for the issue to reach the nation 's highest court , and demonstrated the deep political divisions over the law despised by conservatives intent on undermining it .

Both judges in the majority of the 2-1 D.C. Circuit ruling were appointed by Republican presidents , while all three in the unanimous 4th Circuit panel were appointed by Democratic presidents .

Republicans immediately hailed the D.C. panel 's ruling against the subsidies as evidence of what they called fatal flaws in the health care law .

`` This is yet more evidence that Obamacare is not working -- and can not work -- for the American people , '' said GOP Sen. Lamar Alexander of Tennessee , who faces a conservative primary challenger questioning his right-wing credentials .

At the White House , spokesman Josh Earnest expressed confidence in the administration 's legal position , saying Congress clearly intended for all Americans to have access to tax credits if needed so they could afford health insurance .

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The issue : subsidies

The legal argument involves a provision in the health care law that says people who obtained coverage through state-run exchanges can get federal subsidies such as tax credits . It does n't specifically say that those signing up on the federal exchange also are eligible .

Opponents of the law contend that lack of specificity renders illegal the subsidies for anyone who enrolled through the federal exchange .

Only 14 states and the District of Columbia set up their own exchanges , meaning that the 4.7 million who signed up for subsidized health coverage through HealthCare.gov could be affected .

`` It will kill Obamacare , '' Republican Sen. Orrin Hatch of Utah said of an eventual Supreme Court ruling against the subsidies . `` It would make it very difficult for Obamacare to continue because the cost of health care is going to go sky high for those who are not in the state exchange . ''

For now , the law remains unchanged and the subsidized policies are unaffected until the legal case plays out , Earnest told reporters . The Justice Department said the government would appeal the D.C. panel 's decision .

Partisan divide

The easiest fix -- changing the law to specify that it allows subsidies for coverage purchased through the federal government as well as state exchanges -- would mean reopening the debate in Congress .

Unlike last time , when Democrats held majorities in both the House and Senate , Republicans now control the House and are expected to make gains in the November election , perhaps taking over the Senate too .

That means Obama and Democrats have no chance of getting Congress to approve any remedial change in the law .

Sen. Ted Cruz , R-Texas , one of the leading crusaders against the health care act , argued Tuesday that the federal subsidies amounted to assuming funding powers the Constitution granted Congress .

Earnest , however , said Congress intended `` to ensure that every eligible American who applied for tax credits to make their health insurance more affordable would have access to those tax credits , whether or not the marketplace was operated by federal officials or state officials . ''

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Ambiguity

The opposing rulings Tuesday pivoted over the meaning of the word `` ambiguous . ''

In Richmond , the 4th Circuit judges labeled the Affordable Care Act ambiguous on whether subsidies should be allowed for consumers getting insurance on federal exchanges .

When a law is ambiguous , courts give deference to a federal agency 's interpretation of the law , which in this case is the Internal Revenue Service rule allowing the subsidies .

The D.C. Circuit decision concluded that Obamacare was unambiguous in restricting subsidies to insurance purchased on exchanges `` established by the state , '' rather than the federal exchange .

In his dissent , though , appellate Judge Harry Edwards -- a Democratic appointee -- argued that labeling the phrase `` established by the state '' as unambiguous `` strains fruitlessly to show plain meaning when there is none to be found . ''

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CNNMoney 's Tami Luhby and CNN 's Joe Johns and Bill Mears contributed to this report , which was written by Tom Cohen .

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NEW : One ruling goes against the government , another supports its position

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The rulings reignite the fierce political debate over Obamacare

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For now , nothing changes until the cases completes the legal process

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The issue would impact those who signed up for Obamacare on the federal exchange